The present invention relate to the field of ground speed sensor apparatus, and more particularly to such apparatus for measuring the true ground speed of moving vehicles.
Conventional speedometers pick off the vehicle speed assuming a constant gear ratio from the tire to axle to drive train. If the tire(s) pressure becomes low, or if tires are installed which are larger or smaller in diameter than the original equipment tire size, then the gear ratio, and hence the calibration of the speedometer, changes.
It would therefore represent an advance in the art to provide a ground speed measuring apparatus which is independent of height of the car from the road and any gear ratios.
It would further represent an advance in the art to provide a ground speed sensor for moving vehicles which is compact, has no moving parts, and is rugged.